You're right, you have been wasting your time. Although not with me. The entire premise you've been bitching about is one giant waste. That isn't all I had to say, I made my case with plenty more prose besides, and that was just the icing on the cake for my last response.
The only reason you're saying it's counterituitive to their statements about counterplay is that you aren't at the helm. If you were a Morgana or a LeBlanc main, you'd be singing an entirely different tune. Once again, the fact that LeBlanc is low tier while Morgana is high tier, although not from her ult but from her insane snare duration, shows that clearly the slow on their tethers does not impact counterplay against them so much that it becomes unfair to handle.
Do you have any legitimate reason why they should not? You're the one with the problem, but your only justification thus far has been that there's no counterplay against that mechanic when there's plenty. For instance, if LeBlanc has you tethered, she has to stay within range. She opens herself up to attack. So go all in on her, because chances are if the tether finishes she's going to blow you up otherwise. If you're playing a more mobile champ, just skirt away from it with whatever movement ability it is that you possess.
Their tethers also take much longer to reach completion versus a tether like Nocturne or Karma. You have a wider window to either kill them, or to get away, before you get hit with the CC. If they DIDN'T have the slow, you wouldn't have any issue simply walking away. If they reduced the duration of the tether, it would become too easy to land the CC that comes at the end of it. Putting a slow on a lengthy tether is a middle ground beneath the two. They still have to work for it if they want the full effect, and you still have to work for it if you want to get away. It isn't impossible, it's far from. I've broken plenty more Morgana and LeBlanc tethers than I have been hit by them because even with the slow, it's not that hard to get away. Especially since chances are they're going to try and cast it from the max range they can.
While you accuse me of flexing some fictitious ego, you're too busy condescending to realize you're almost ferally stroking at your own. I am not a god that deals with anything, but I'm a player who can step back and look at the design of a champion objectively. If you had really thought any of this through as much as you're trying to make it seem, you should have supplied an alternative that details where else in their kit this power would shift.
As it stands, you have not. You have voiced a problem and posed as though you have the solution when you haven't even the faintest idea of what the compensation for removing the problem you're voicing even is. You're treating CC + tether as though it's this horrible, uncounterable mechanic when in all reality it isn't going to be the reason that either of those champions are ever considered overpowered if they ever do become labeled that. It gives them ways to make plays, and makes you have to work a little bit harder to get away from them to keep yourself from getting caught in one.
Boo freaking hoo.
As it stands, the tethers aren't the part of their kits that cause issues when either of them are dominating in a match they're in. That remains LeBlanc's overwhelming damage potential, and Morgana's ability to essentially turn off an enemy champion during a team fight from a stupid long distance.
If you want to talk about the problem, then you should probably have thought it out well enough to offer up a solution as well. There's nothing to be gained from whining about the issue and calling for change but not saying what that change could be, more so over a mechanic that isn't even that awful to deal with. Sucks to be caught in, but if you're stuck in it it's because you were caught out without any mobility options. Not because the slow is counterintuitive. It's a part of their playstyle, whether you like it or not. Part of what defines them as champions. There's a limit where removing something for the sake of balance instead changes the way a champion plays as a whole.
Until the slows on their tethers become notably, and unfairly, difficult to play against, they don't have to be altered. The slows aren't what win either of them matches. That still falls to the skill of the player and of the enemy they're trying to kill.
Or next I suppose you're going to be complaining that the added slow on Diana's knockup is too much CC. Or that Wukong's ult is counterintuitive because if you get knocked up by it you're stuck taking damage afterwards and there's "no counterplay" for that either.
Thus far the only thing you've succeeded in doing was pointlessly complaining about a mechanic that no one else seems to have a problem with. It's not even a concern for most players. It is a part of the tactical decisions that make up this game, starting in champion select. There are ways to render them ineffective, and ways to make it so that you can't do anything to stop them, starting from the moment champions are being picked for the match. If you happen to pick someone with no means of getting away, oh well. It was the choice you made, and not everyone is going to be able to get away from everyone else. That's part of the game. But so long as there are still viable options of handing the situation at hand, it doesn't need to be altered. It isn't oppressive, it isn't "anti fun", and there are still enough counterplay options to keep you from being completely wrecked in all cases in a fashion that is unfair to you as a player or biased towards them as a champion.